World Gravity Anomaly Maps

Frédéric Chambat
Laboratoire de sciences de la Terre, ENS-Lyon, 46 allée d'Italie, 69364 LYON cedex 07, France
Phone : (33) 4 72 72 85 56, Fax : (33) 4 72 72 86 77.
Click here to , go to my geophysical homepage.


Since global gravity maps are not so easy to find, I made some of these. I computed the anomalies from the EGM96 geopotential model, which is a spherical harmonic model of the Earth's gravitational potential complete to degree and order 360. The potential of an hydrostatic ellispoid model was subtracted. The summation was carried up to degree 360, on a 0.5x0.5 degree grid. The maps were drawn with the GMT sofware. They differ only by the type of projection (cylindrical or Hammer), the color palettes ("polar" or "haxby"), the scale (continuous or discontinuous) and the centering (Greenwich or Pacific). My prefered ones are the cylindrical continuous. The scale is chosen in order to take into account that extreme values of anomalies are approximately +/- 300 mGal and that most of the signal is within +/- 100 mGal.

These maps represents the Free Air Gravity Anomalies. Clik on these images to see larger maps.

Enjoy !

First, the cylindrical projections :
(some parralels miss on these images but appear on larger maps, I don't know why.)

Greenwich centered

Pacific centered

Haxby
continuous
palette



Haxby
discontinuous
palette



Polar
continuous
palette



Polar
discontinuous
palette




Second, the Hammer projections:

Greenwich centered

Pacific centered

Haxby
continuous
palette



Haxby
discontinuous
palette



Polar
continuous
palette



Polar
discontinuous
palette



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End of page, F.C. 2004